THE WATER SCAVENGER BEETLES. 



247 



Subseries D. T RIMER A CLAVICORNIA. 



The members of this group have the tarsi all 3-jointed and the 

 ventral segments free. They live either in fungi or feed upon plant 

 Kce. The following families of the subseries are represented in the 

 State : 



KEY TO INDIANA FAMILIES OF TRIM ERA CLAVICORNIA. 



a. Wings fringed with long hairs ; abdomen not prolonged and with 6 or 7 

 ventral segments ; antennae with the basal and apical joints thicker 

 than the middle ones, the latter with whorls of long hairs ; length 

 less than 2 mm. Family XII. Trtc h opteb ygidje , p. 485. 



aa. Wings not fringed. 



b. Tarsi with second joint dilated; third joint consisting really of two 

 joints, the small true third joint being inserted at the base of the 

 last joint. 



c. Tarsal claws dilated or toothed at base ; first ventral segment with 



coxal lines ; form* usually rounded and convex ; head nearly con- 

 cealed by the thorax ; last joint of maxillary palpi usually 

 hatchet-shaped; length less than S.5 mm. 



Family XVI. Coccinellid.e, p. 50G. 

 cc. Tarsal claws simple; first ventral without coxal lines; form oblong 

 or oval, rarely globose; last joint of maxillary palpi oval or tri- 

 angular ; length less than 6.5 mm. 



Family XVII. Endomychule, p. 533. 

 l)l>. Tarsi with second joint not dilated and without a pseudo fourth 

 joint. 



d. Elytra entire; ventral segments nearly equal; front coxal cavities 



rounded, not prolonged on the outer side ; length less than 3 mm. 



Family XXVII. Lathridiid/E, p. 651. 

 dd. Elytra truncate behind, leaving the pygidium exposed ; ventral seg- 

 ments 1 and 5 longer than the others ; front coxaa small, rounded ; 

 length less than 3 mm. Family XXIX. Monotomid^, p. 666. 



Family VI. HYDROPHILID^E. 



The "Water Scavenger Beetles. 



This family comprises, for the most part, oval or elliptical black- 

 ish beetles, differing from the Dytiscidae in being more convex, in 

 having the antennae ending in a distinct club instead of being fili- 

 form, and in possessing palpi which are usually longer than the an- 

 tennae and are projected forward while swimming, while the an- 

 tennae are usually concealed beneath the head. By the inexperi- 

 enced student the palpi are, therefore, often mistaken for the an- 

 tennae. 



The name of the family is derived from the genus Hydrophilus, 

 a word of Greek origin meaning ' ' a lover of water. ' ' As the name 



